function add_class_name(element, class_name) {

	var classes = element.className.split(/ +/);

	var found = false;

	for (var i = 0; i < classes.length; i++) {

		if (classes[i] == class_name) {
			found = true;
		}

	}

	if (found == false) {

		element.className += (' ' + class_name);

	}

}

function remove_class_name(element, class_name) {

	var classes = element.className.split(/ +/);
	var new_classes = new Array();

	for (var i = 0; i < classes.length; i++) {

		if (classes[i] != class_name) {

			new_classes[new_classes.length] = classes[i];

		}

	}

	element.className = new_classes.join(" ");

}